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"The reason behind this crash is packet size. By default, MySQL configuration max_allowed_packet is set it to 16M. This settings may introduce this exception in your website..

Solution:
To resolve that problem you needs to increase max_allowed_packet variable in MySQL. Add following line in my.ini 

max_allowed_packet=100M 

Save the file and restart MySQL service. Now onward you will never get that kind exception in your open source / website."

"This error also presents as "Cannot modify header information" depending on PHP version.

In short, it means that somewhere in the code, something was printed to the browser before Drupal had finished preparing the page. This is most often caused by custom or modified code contributed from sources outside Drupal, so inspect your uniquely added code (including themes) first..

If you get a "Headers already sent" error, there are three likely causes.

This is some explaination:

1) The issue is with 'max_allowed_packet' just increase the limit to 16M

Here are the steps to do that

1. Go to xampp\mysql\bin
2. Open my.ini
3. Change "max_allowed_packet" from "1m" to "16m" (or larger)
4. Save my.ini Now restart MySql through the XAMPP control panel

Note: But this one for development, what about live server?

* Source: https://www.drupal.org/node/1537488